Copernicus: Peculiar start to the 2019 ozone hole season
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In the lead-up to the UN’s International Day for the Preservation of the Ozone Layer, the Copernicus Atmosphere Monitoring Service (CAMS) starts to register activity in the Antarctic
The Copernicus Atmosphere Monitoring Service (CAMS), implemented by the ECMWF on behalf of the European Union, contributes to the international efforts of preserving the ozone layer by continually monitoring and delivering high quality data about its current state. The ozone layer resides in the stratosphere, high up in our atmosphere, approximately 15 to 35 kilometres in altitude, and acts as a shield to protect human life from the effects of harmful ultraviolet radiation.
CAMS data reveals that the ozone hole in Antarctica has begun to form approximately two weeks earlier than expected, compared to the previous years. This year’s episode is also peculiar, because the CAMS data show that the ozone hole is currently off-centric and forecasts indicate signs of instability due to substantial dynamical activity in the relevant portion of the stratosphere. As a result, the spatial extent of the ozone hole is currently progressing at a substantially slower pace than usually seen. This may lead to a smaller and possibly shorter ozone hole episode.
The ozone hole first appeared decades ago, caused by harmful man-made emissions into the atmosphere of chemicals arising from aerosols, refrigerants, pesticides and solvents.
The International Day for the Preservation of the Ozone Layer was created by the United Nations to commemorate the signing of the Montreal Protocol in 1987 by 196 states and the EU, in which the main ozone-depleting chemicals were banned.
The UN day will take place on 16th September and this year’s “32 Years and healing” to mark the gradual healing of the ozone hole. In the lead-up to the day and beyond, CAMS will be monitoring the hole’s formation on a day-by-day basis. The service also producesforecasts on how the ozone hole is likely to look five days ahead.
CAMS’ operational monitoring of the ozone layer, using computer modelling in combination with satellite observations in a similar way to weather forecasts, can give a clear idea whether and how the ozone layer is healing over time as a result of the Montreal Protocol and its amendments that have banned the use of the main ozone-depleting chemicals.
Each year at the start of the Austral Spring in September, the Antarctic sees a resurgence of the ozone hole. This happens because during the Southern Hemisphere’s winter, the entire polar region is in darkness, causing a particular wind pattern, called a vortex, to form. Chemical substances accumulate within the polar vortex and remain inactive in the dark, where temperatures can fall to below -78 degrees. When the sun rises over the pole, the sun’s energy releases the formerly chemically inactive atoms into the vortex, which then, now chemically active, rapidly destroy ozone molecules and cause the ozone hole to form. 
CAMS information products aid observation of the ozone hole development from about mid-July until it dissolves, generally in late November or December. The ozone hole usually reaches its maximum between mid-September and early October. According to the 2018 Scientific Assessment of Ozone Depletion produced under the auspices of the WMO, recovery of the ozone layer to pre-1970 levels will occur around 2060.
“There is no cause for complacency,” comments Vincent-Henri Peuch, Head of the Copernicus Atmosphere Monitoring Service (CAMS). “The recovery of the ozone layer is dependent on climate change as long-term cooling in the stratosphere can exacerbate ozone loss and delay the process. Also, the possibility of unauthorized emissions of ozone depleting substances cannot be ruled out – indeed, emissions of the second most abundant chlorofluorocarbon (CFC-11) have been detected in 2018 and they could be traced back unequivocally and action be taken. It is very important to maintain international efforts for monitoring the recovery of the ozone layer and the ozone hole events.”
More information and a 3D animation of the current status of the ozone hole is available on the CAMS website at: https://atmosphere.copernicus.eu/monitoring-ozone-layer
 Chlorine and bromine-containing substances accumulate within the polar vortex where they remain chemically inactive in the darkness. Temperatures in the vortex can fall to below -78 degrees Celsius and ice crystals in Polar stratospheric clouds can form, which play an important part in the chemical reactions. As the sun rises over the pole, the sun’s energy releases chemically-active chlorine and bromine atoms are released in the vortex which rapidly destroy ozone molecules and cause the hole to form.